SA Dermatology Definitions Flashcards
Macule
Circumcised, non-palpable spot, change in the color of the skin
Papule
Small, elevation of the skin (1 cm), palpable solid mass
Pustule
Small, circumcised elevation of the epidermis filled with pus
Vesicle
Sharply circumcised elevation of the epidermis filled with clear fluid
Wheal
Sharply circumcised, raised lesion with edema
Appears and disappears within minutes or hours
Nodule
Circumcised, solid elevation >1 cm in diameter, extends into the deeper layers of the skin
Tumor
A large mass that may involve any structure skin or SQ tissue
Alopecia
Loss of hair, partial to complete
Scale
Accumulation of loose fragments of the horny layer of the skin
Crust
Formed when dry exudate, serum, pus, blood, cells, scales, or medication adhere to the surface
Comedo
Dilated hair follicle filled with cornified cells and sebaceous material
Epidermal collarette
Special type of scale arranged in a circular rim of loose keratin flakes or peeling keratin
Hyperpigmentation
Increased epidermal +/- dermal melanin
Excoriation
Erosions or ulcers caused by scratching, biting, or rubbing
Erosion
Shallow epidermal defect that doesn’t penetrate the basal laminar zone
Heals without scaring
Ulcer
Break in the continuity of the epidermis with exposure of the dermis
Fissure
Linear cleavage into the epidermis or through the epidermis into the dermis, caused by disease or injury
Lichenification
Thickening and hardening of the skin, exaggeration of the superficial skin margins
Layers of the skin
Epidermis (top)
Dermis
Subcutaneous tissue
Epidermis
Keratinocytes (major cell type)
Melanocytes (produce melanin)
Langerhans (Ag-presenting cells)
Layers of the epidermis
Basal layer (cell division)
Spinous layer (desmosomes, cell differentiation)
Granular layer (keratohyalin granules)
Horny layer/ S. Corneum (barrier/ cornified layer)
______________ is only found in the footpads and nasal planum only
Clear layer (S. Lucidum)
Dermoepidermal Junction
Separates epidermis from the dermis
Layers: basal keratinocytes, lamina lucida (proteins), lamina dense (type 4 collagen), sub lamina densa (anchoring fibrils)
Dermis
Supports and nourishes the epidermis
Complex matrix of fibers (collagen, elastin, reticulin, muscle)
Ground substance (glycosaminoglycans)
Innervation from myelinated spinal nerves
Cells found in the dermis
Fibroblasts (produce collagen)
Mast cells (binds IgE, Ag attaches, mast dell degranulation- type 1 hypersensitivity)
Histocyte (macrophages)
Subcutaneous tissue
Fat with CT, BVs and nerves
Fat storage, heat insulation and body contour (shape)
Epidermal appendages
Sebaceous glands (secrete sebum)
Sweat glands
Hair follicle and hair
Sweat glands
Apocrine for thermoregulation
Eccrine found on footpads
Hair follicle growth phases
Anagen (growth)- breeds that needing grooming in this phase
Catagen (intermediate)
Telogen (resting)
Primary lesions
Macule/ patch
Vesicle/ bulla
Tumor/cyst
Wheal
Nodule
Pustule
Plaque or papule
Secondary lesions
Epidermal collarette
Scar
Excoriation
Erosion/ ulcer
Fissure
Lichenification
Callus
Lesions that may be primary or secondary
Alopecia
Scale
Crust
Follicular casts
Comedo
Pigmentary abnormalities
